The long range purpose of the project is to study the biochemistry, morphology, pharmacology and physiology of inner ear neurons and cells and of their interactions and to describe the mechanisms behind these interactions. The interest is now focused on: 1) the isolation and characterization of cochlear transport proteins, which has led to the purification of carbonic anhydrase from the cochlear membranous lateral synapses, as seen under the electron microscope in thin sections and in freeze-fracture replicas; 3) the levels of choline acetyltransferase (ChAc) and glutamate decarboxylase (GAD) in the cochlea, with findings fitting the hypothesis that the olivocochlear nerve fibers are cholinergic and that GABA is unlikely to be a transmitter in the organ of Corti; 4) the in vitro uptake of amino acids (glutamic acid, aspartic acid, GABA, glycine and leucine in the inner ear of guinea pig); 5) the levels of choline acetyltransferase in the normally developing inner ear and in the inner ear of a genetically deaf mutant (the waltzing guinea pig).